Antenna switching system



g 1952 P. A. GUARINO EI'AL 2,607,008

ANTENNA SWITCHING SYSTEM Filed Aug. 9, 1945 2 SHEETS-SHEET 1 4 P ANTHONYGUARINO ROBERT J. ADAMS JOHN W. FRAUMANN LEE R. DOBLER Aug. 12, 1952Filed Aug. 9, 1945 P. A. GUARINO EI'AL 2,607,008

ANTENNA SWITCHING SYSTEM 2 SHEETSSHEET 2 P. ANTHONY GUARINO ROBERT J.ADAMS JOHN W. FRAUMANN LEE R. DOBLER Patented Aug. 12, 1952 ANTENNASWITCHING SYSTEM Pasquale Anthony Guarino and Robert J. Adams,Washington, D. 0., and John W. Fraumann and Lee R. Dobler, United StatesNavy Application August 9, 1945, Serial No. 609,909

3 Claims.

(Granted under the act of March 3,1883, as

amended April 30, 1928; 370 0. G. 757) or the other of. a given line ofbearing.

An object of this invention is to provide a simple means of angularlydeflecting the beam 'of such an antenna system pattern.

It is anotherobject of the present invention to provide a satisfactorydivision of the radio frequency power among the elements of an antennasystem formed of three radiators.

A further object of the invention is to provide an antennalobe-switching system of simple and inexpensive constructionWhlCh?'C2.I1 be assembled with a minimum number of circuit components,and without the use of expensive and specially designed apparatus.

' It is well known that the direction of the main beam of a directiveantenna array depends upon the phase relation of the currents flowing inthe several radiators comprising the antenna system. Various methodshave been proposed hitherto for feeding the different radiators of anantenna array with currents having the desired phase variation. Thecommon practice depends upon feeding all the radiating elements from asingle feed line through paths of different electrical lengths.

According to the present invention an antenna comprising three verticaldipole radiators is used to alternately transmit and receiveradio-frequency signals. The center radiator is fed by a line whoselength remains unchanged. The electrical length of the feed line to eachof the outer two radiators is alternately made shorter then longer thanthe length of the feed line to the center radiator. By this means theradiofrequency currents are phased so that the phase of the currents inthe center radiator lies between the phases of the currents present inthe outer radiators with first one then the other of the outer radiatorsbeing ahead in phase. In this way the beam is made to deflect first toone side, then to the other of a normal line of bearing.

The alternation of the order of the phases of the currents in theradiators is accomplished by means of a switch mechanism includingtwo'pairs of contact points which are alternately operated to cause oneor the other of two short sections of transmission line to beelectrically grounded so that when thus connected it is effectivelyremoved from the circuit. The details of the cirtwenty-five electricaldegrees.

2 cuit arrangement for effecting these desirable results Will behereinafter described in greater detail in the more specific descriptionwhich subsequently follows:

A better understanding of the objects, features and advantages of thisinvention will be had from the particular description of a preferredembodiment thereof made with reference to the accompanying drawing,inwhich:

Figure 1 is a schematic diagram of one embodiment of the invention; 1

Figure 2 shows a modified form of the invention; and

Figure 3 is a perspective view of the mechanical switching device, shownpartially in section, and constructed in accordance with the invention.

Referring now to Fig. 1 of thedrawing, the outer radiators Ill and I2may comprise vertical dipoles which are respectively connectedelectrically to two transmission line sections [5 and I6 of equallength. The radiator I0 is connected to a junction point 13 through thesections of transmission line I5, I! and I8. The other outer radiator I2is connected to the point I3 through the sections of transmission linel6, l9 and 20. The impedances of the sections 15 and Iiiare matched tothe radiators l0 and I2. The sections l1 and [9 each are quarter-wavetransformers of the same characteristic impedance, Zo, as thetransmission line sections 15 and [6. The sections it and 20 each are aquarter-wave length also and the characteristic impedance of each isapproximately equal to Z0 /2. It will be ob served that standard 52and'75 ohm coaxial lines will meet these impedance requirements. A thirdquarter :wave section of transmission line desi nated as line 22, ofthis latter characteristic impedance, Zo /2, connects the junction pointl3 with the branch point 23. Another quarter-wave transformer 24 ofcharacteristic impedance Zo\/2, is used between this branch :point 23and the line 25 leading .to the central vertical dipole radiator 26.Line 25 is of characteristic impedance Zo, and is matched to theradiator 26. A

short phasing section of line 2! of impedance Z0, is bridged between thepoints 28;and 29, thereby connecting the outer radiators togetherthrough the lines 15, 21 and IS. The length of this phasing section maybe of the order of one hundred The exact length required depends uponthe phase difierence desired between the currentsin the two outerradiators. The length of the line 25 and the transformer 24takenasafunit 'is equal to rents in radiators i and I2.

the electrical length of line from point 23 through the lines 22, 28, I9and Hi to the radiator |2 plus one half the length of the phasingsection 21. Contact points 30 and 3| are provided for groundingalternatelythe midpoints of the half-wave sections of line made up ofthe quarter-wave length pairs I8 and I9, 20. From the branch point 23 aline 35 of impedance Z0 is run to the transmitter and/ or receiver 36.

In Figure 3 there is shown one practical'form of lobe switch whichcomprises a metallic shield or box 49 housing a rotatable-cam 4| whichupon rotation by a motor (not shown) alternately makes and breaks thepairs of contact points 30 and 3|, one of each pair'being movable andcarried by the cam-actuated rocker arms 42 and 42 respectively. Thestationarycontact point of each pair is electrically connected bymeans-of the respective adjustable screw-threaded conductors 43 and 43'to the inner conductor 44 of "the associated short coaxial line sections45 and "45 at the respective junction points 31 and 38 thereof.Restoring springs 45 of flat conductive strip material complete theconnection of the movable contacts to ground, the length of thesewhereby they will be readily distinguishable from a *an y'sig'nalsreceived when the radiated beam is deflected to the otherside.

Itis' to be understood that an M4 sections of "line may be any oddnumber of quarter-wave lengths, and that all 7J2 sections may be any'int'egral'number of 'half-waves. However, if the -=antennalobeswitching system is to operate suceessfuny' over a band of frequencies,the lengths specified are preferable.

During operationof the beam switching circuit the half-wave sectioncomprising the lines Hand 18 is grounded through the set of contactpoints '3U"fol1owing which the set of contact points 3| is opened;Thereafter because of the ground connection made through contactpoint'30, the impedances' at'points l3 and 28 looking toward-thegrounding contacts are quite high; hence,for all practical purposes, thehalf-wave-section between the points-|3 and 28 may be regarded as beingout of the circuit so that radio-frequency currents entering the line 22would go by way of sections 20 and Hi to the junction point 29 wherethey would divide. The currentsgoing by way of the phasing section 21through line l to radiator Ill will lag the currents in radiator I 2 byan amount essentiallyz-equal-to the electrical lengthof section 21. Aswas pointed out above the path'from point 23 to radiator 26 is longerthan'the path from point 23 to radiator l 2 by way of sections 22, 20,I9 and It. This difference in 'length causes the currents in radiator 26to be phased substantially half-way between the cur- Operation of theswitching system to close the points 3| and open the points 30-serveseffectively to remove the sections l9 and 20 from the circuit by makingthe "pointsfi and 2'! points of high impedance. Currents entering thesection of line 22 are then obliged totake the path through sections Hiand 11 to the junction point 28. Under .these circumstances the currentsin radiator l0 lead the currents in radiator l2. Therefore, the currentsin radiator 26 now lag the currents in ID and lead the currents in l2.

If we assume the contact points 30 open and points 3| closed, theimpedance seen at junction 28 looking toward the radiators will be Thequarter-wave transformer I! of impedance Z0 will transform thisimpedance to 2Z0 at point .31. Since sections l8 and 22 are eachquarterwave sections of line comprising together a halfwave transformer,the impedance at point 23 looking toward point I3 is likewise 2Z0. Theimpedance at point 23 lookin toward radiator 26 is 220, beingtransformed from Z0 by the quarter-wave transformer 24 of impedanceZo\/2. The impedances looking toward the radiators are paralleled at thejunction point 2 3 and therefore will match the line 35 of impedance Z0.

It will be noted that the impedances of the outer radiators as seen frompoint 28 when the contacts 3| are closed or from point 29 when thecontacts 30 are closed are each Z0. Therefore, the radio-frequency powerleaving points 28 or 29 will be divided approximately equally betweenthese radiators. Now, since the impedances looking into lines 22 and 24from point 23 were each equal to 220, the power leaving point '23 willbe equally divided. The center radiator therefore receives the samepower as the outer two radiators combined.

The power division thereby obtained plus the phasing of the radiatorcurrents provided by the switching system herein described produces abeam of moderate width'whose axis is shifted through a small angle asthe phase order of the radiator currents is reversed.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

1. In a directive antenna system, a central set of radiators and twoside sets of radiators, a transmission line joining said side sets ofradiators, a pair of transmission lines electrically an integral numberof half-wave lengths long having one pair of ends thereof connected atdifferent points on said transmission line equally distant from saidside sets of radiators and the other pair of ends thereof joined at acommon junction point, a feed line, a quarter-wave line connecting saidcommon junction point to said feed line, a pair of grounding contacts ineach line of said pair of'transmission lines located an odd number ofquarterw-ave lengths from said common junction point, means foralternately rendering each pair of grounding contacts effective andineffective so that the pair of transmission lines are alternatelyrendered conductive and non-conductive to passage of radio frequencyenergy, a transmission line joining the central set of radiators to saidfeed line through impedance transformer means connected to the junctionpoint of said quarter-wave line and said feed line, and impedancetransformer means included in the portion of each line of said pair oftransmission lines between said grounding contacts and said commonjunction point.

2. In a directive antenna system, a central set of radiators and twoside sets of radiators, a

transmission line matched to said side sets of radiators, a first pairof quarter-Wave transmission lines having characteristic impedancescorresponding to the characteristic impedance of said transmission lineconnected at diirerent points o said transmission line equally distantfrom said side sets of radiators, a second pair of quarterwavetransmission lines eachh-aving characteristic impedances equal to theproduct of the square root of two and the value of said characteristicimpedance connecting said first pair of transmis-' sion lines to acommon junction point, a feed line having a characteristic impedancecorresponding to said characteristic impedance, a quarter-wave linehaving a characteristic impedance corresponding to the characteristicimpedance of said second pair of quarter-wave transmission linesconnecting said common junction point to said feed line, a transmissionline matched to the cen-- tral set of radiators, .a quarter-wave linehaving characteristic impedance corresponding to the characteristicimpedance of said second pair of quarter-wave transmission linesconnecting the last-named transmission line to said feed line at thejunction point thereof with said quarter-wave line, and meansalternately grounding the mutually connected ends of the transmissionlines of said first and second pair of quarter-wave transmission lines.

3. In a directive antenna system, a central set of radiators and twoside sets of radiators, a transmission line joining said side sets ofradiators, a pair of transmission lines electrically an integral numberof half-wave lengths long having one pair of ends thereof connected atdifferent points on said transmission line equally distant from saidside sets of radiators and the other pair of ends thereof joined at acommon junction point, a feed line, a quarter-wave line connecting saidcommon junction point to said feed line, a transmission line joining thecentral set of radiators to said feed line through impedance transformermeans connected to the junction point of said quarter-wave line and saidfeed line, impedance transformer means included in each line of saidpair of transmission lines, and means for alternately rendering saidpair of transmission lines conductive and non-conductive to passage ofradio frequency energy, the last-named means including two adjustablestationary contact points, an electrical connection between a selectivepoint on one of said pair of transmission lines and one of saidstationary contact points, an electrical connection between a selectivepoint on the other of said pair of transmission lines and the other ofsaid stationary contact points, one movable contact in cooperatingrelationship with the said one of said stationary contact points, asecond movable contact in cooperating relationship with the other ofsaid stationary contact points, two rocker arms carrying said movablecontact points, a cam for operating said rocker arms, restoring springsfor said rocker arms in contact with said cam, and means for rotatingsaid cam.

JOHN W. F'RIAUMANN. LEE R. DO'BLER.

P. ANTHONY GUARINO. ROBERT J. ADAMS.

REFERENCES CITED The following references are of record in the file ofthis patent:

. UNITED STATES PATENTS Number Name Date 2,243,566 Kimball May 27, 19412,397,645 Brown Apr. 2, 1946 2,408,779 Jenks et al. Oct. 8, 19462,411,034 Gluyas, Jr. Nov. 12, 1946 6 V I i

